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近年来,难降解有机污染物的降解问题引起了人们的广泛关注,因为它们对自然环境和人类健康造成了极大的危害[1]。特别是,煤化工生产过程产生的高浓度盐水中含有大量的难降解的有机物(如PAHs、杂环化合物等),这些物质通常具有复杂的芳族分子结构,这使得它们更稳定并且更难以降解。如果不加以处理,这些有害物质会引起某些健康危害和环境污染[2]。虽然传统的处理技术,如物理吸附[3-4],化学氧化[5]和生物方法[6],已经研究从废水中去除难降解有机物,但许多问题仍然是不可避免的,如二次污染[7]和伴随污染物的生物降解延迟[8]。高级氧化过程(AOPs),定义为利用羟基(·OH)进行氧化的那些技术[9-10],在过去几十年中,这些技术在废水处理技术的研究中受到越来越多的关注。这些过程(如光催化氧化,芬顿化学和臭氧催化氧化[11-12])已成功应用于去除或降解顽固污染物,或用作预处理将污染物转化为短链化合物,然后再通过常规或生物方法处理[13]。其中之一的经典方法是非均相臭氧催化氧化工艺,它利用不溶性催化剂对有机污染物进行氧化还原和矿化,臭氧催化氧化因其效率高、操作简单而被认为是一种很有前途的工艺[14-15]。这一过程的关键因素是制备有效的非均相催化剂,因此,须进一步探索研究,以找出廉价、高效和稳定的非均相催化剂,在催化臭氧氧化中高效降解有机物污染物。
因此,本研究采用浸渍-煅烧法制备了负载活性金属氧化物的活性氧化铝型催化剂,以煤化工高浓盐水为目标污染物,探索催化剂的制备工艺和反应操作条件对高盐废水COD去除率的影响,为高效的臭氧催化体系的开发及其在煤化工高盐废水处理领域的应用提供参考。
煤化工高盐废水臭氧催化氧化脱除COD
COD removal from high-salt wastewater in coal chemical industry by ozone catalytic oxidation
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摘要: 针对煤化工高盐废水中有机物难降解问题,采用浸渍-煅烧法制备了负载有活性金属氧化物的活性氧化铝型催化剂,探索催化剂的制备工艺和反应操作条件对废水COD去除率的影响。结果表明:活性氧化铝载体催化性能优于陶粒,活性氧化铝负载Cu、Mn、Ni的催化活性较高,将2种活性组分进行组合制得的MnOx-NiOx/γ-Al2O3催化剂,在经过60 min的臭氧催化氧化后,COD的去除率可达51.3%;利用BET、SEM-EDS、XRD对催化剂进行了表征和分析,Mn、Ni成功负载到活性氧化铝表面和孔隙内,2种元素负载量摩尔比约为2∶1,且主要以氧化物形式存在;通过计算臭氧利用效率,发现MnOx-NiOx/γ-Al2O3臭氧催化氧化的η值低于单独的臭氧氧化,这意味着通过MnOx-NiOx/γ-Al2O3催化剂可以有效地将臭氧分解成活性氧;通过优化臭氧和催化剂投加量后发现,在臭氧为350 mg·(L·h)−1、催化剂投加量为100 g·L−1废水中,反应180 min后,COD去除率可达到72.3%;在连续进行4 h的臭氧催化氧化实验后,MnOx-NiOx/γ-Al2O3稳定性和重复利用性均较好,COD去除率能维持在约42%,锰、镍离子的溶出量均小于0.5 mg·L−1。以上研究结果可为高效的臭氧催化体系在煤化工高盐废水处理领域的应用提供参考。
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关键词:
- 煤化工高盐废水 /
- MnOx-NiOx/γ-Al2O3催化剂 /
- COD去除率 /
- 臭氧催化氧化
Abstract: Aiming at the problem of refractory degradation of organic matters in high-salt wastewater from coal chemical industry, an active alumina-type catalyst loaded with active metal oxide was prepared by an impregnation-calcination method. The effects of catalyst preparation and reaction conditions on COD removal rate from wastewater were investigated. The experimental results showed that the catalytic performance of activated alumina carrier was better than that of ceramsite, and activated alumina supported with Cu, Mn, Ni had high catalytic activity, of which the MnOx-NiOx/γ-Al2O3 catalyst prepared by the combination of the two active components could catalyze the ozone oxidation reaction with 51.3% COD removal after 60 minutes. The catalyst was characterized and analyzed by BET, SEM-EDS, XRD. The results showed that Mn, Ni elements were successfully loaded on the surface and pores of activated alumina, and their molar ratio was about 2∶1, and their oxide forms mainly appeared. Through calculating the ozone utilization efficiency, the η value of the MnOx-NiOx/γ-Al2O3 catalyst was lower than that of ozone alone. This implied that the MnOx-NiOx/γ-Al2O3 catalyst could effectively decompose ozone into ROS. After optimizing the dosage of ozone and the dosage of the catalyst, the optimum dosages of catalyst and ozone were 100 g·L−1 and 350 mg·(L·h)−1, respectively, at which the COD removal rate could reach 72.3% after 180 min reaction. After 4 hours ozone catalytic oxidation, the stability and reusability of MnOx-NiOx/γ-Al2O3 were good, COD removal rate maintained about 42% and the release amounts of manganese and nickel ions were less than 0.5 mg·L−1. This study can provide a reference for the development of an efficient ozone catalytic system and its application in the field of high-salt wastewater treatment in the coal chemical industry. -
表 1 实验水样基本水质
Table 1. Basic water quality of experimental water samples
水样
序号pH 电导率/
(mS·cm−1)TDS/
(g·L−1)氯离子/
(mg·L−1)COD/
(mg·L−1)1 8.09 14.10 7.05 3 400 457~665 2 7.55 2.97 1.50 570 126~272 3 8.36 4.57 2.28 1 040 285~437 -
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